Good day all.
I just finished building my cnc mill. Problem is the connection gets lost when I try to connect in universal gcode sender. I have to unplug usb cable and put it back a couple of times before it connects again, but only stay connected for a short while. I have tried it on two different computers with the same result.

I tested the tb6560 controllers with continuity, and get continuity from ground wire to heatsink on x and y controllers. Do not know if its a problem with the controllers.

I have arduino uno and 3 tb6560 controllers. Two 12v 15amp power supplys in series, and 3 nema 23 3amp steppers.

Any help will be appreciated. Thank you